Lobe gear pump



Nov, 18, 1969 w. J. BANGS 3,478,693

LOBE GEAR PUMP Filed April 29, 1968 2 Sheets-Sheet l INVENTOR WALTER J.BANGS ATTORNEYS Nov. 18, 1969 w. BANGs 3,478,693

LOBE GEAR PUMP Filed April 29, 1968 2 Sheets-Sheet 2 INVENTOR WALTER iBANGS ATTORNEYS 3,478,693 Patented Nov. 18, 1969 United States PatentOffice 3,478,693 LOBE GEAR PUMP Walter J. Bangs, Chicago, Ill., assignorto Tuthill Pump Company, a corporation of Delaware Filed Apr. 29, 1968,Ser. No. 725,083 Int. Cl. F04c 1/06 US. Cl. 103126 14 Claims ABSTRACT OFTHE DISCLOSURE Unidirectional flow lobe gear pump which is in cartridgeform and which is mounted for limited axial movement between a coverelement and a drive shaft. This compensates for unsquare ends of driveshafts and also compensates for end play in the drive shaft duringrotation thereof. A porting arrangement reduces impact forces in thepump during shifting of the ports by a port plate and provides forbetter reversing reliability.

The present invention is directed to new and useful improvements inunidirectional flow lobe gear pumps.

Pumps of this general type have been known for many years andcharacteristically include an outer gear and an inner gear positionedeccentrically with respect to the outer gear so that upon rotation ofthe gears, pressure developed between the lobes of the inner and outergears impel fluid therebetween and from an inlet to the intergear spacesto an outlet therefrom. Pumps of this type sometimes have a rotatableport plate which is adapted to change the direction of the porting upona change in direction of the drive of the gear so as to maintain thesame direction of flow from the inlet to the outlet irrespective of thedirection of rotation of the drive shaft. In this type of pump, the portplate rotates through approximately 180 upon a shift in the direction ofdrive shaft rotation. Some stop means must necessarily be provided tolimit the rotation of the port plate and the inertia developed throughthis relatively long (180) travel of the port plate can result indamaging shock forces to be absorbed by the pump elements. Also, inpumps of this general class some provision must be made for aligning thepump with the drive shaft and accommodating the thrust forces developedin the pump due to the eccentric mounting of the inner gear with respectto the outer gear.

With the foregoing in mind, the major purposes of the present inventionare to form a unidirectional flow lobe gear type of pump in such amanner that the elements of the pump may be assembled as a cartridge andmounted easily within a surrounding housing and cover member withrelatively loose tolerances therebetween, to so arrange a pump cartridgeof this type that it is supported over the drive shaft to insurealignment between the main axis of the pump and main axis of the driveshaft, to so arrange a pump cartridge of this type that it is easilyconnected to and disconnected from a drive shaft, to so arrange a pumpof this class as to minimize shock forces in the pump during shifting ofthe port plate within the pump, and to so arrange pumping elements thatthe pumping unit may be simply and economically manufactured, these andother purposes being more apparent in the course of the ensuingspecification and claims when taken with the accompanying drawings, inwhich:

FIGURE 1 is a sectional view of a pump incorporating the principles ofthe present invention;

FIGURE 2 is a diagrammatic view of the pump elements illustrated inFIGURE 1 to illustrate the flow through the pump and with certainelements displaced from their normal position to illustrate the flow;

FIGURE 3 is an end view of the pump of FIGURE 1 taken along the sectionlines 33 of FIGURE 1 and illustrating one position of a rotatable portplate corresponding to a clockwise direction of rotation of the driveshaft;

FIGURE 4 is an end view similar to FIGURE 3 but illustrating theposition of the port plate and other passages when the drive shaftdrives the pump in a counterclockwise direction;

FIGURE 5 is an end view of the pump looking from the drive shaft side ofthe pump;

FIGURE 6 is a sectional view of a modified form of pump assembly; and

FIGURE 7 is an end view of pumps made in accordance with the showing ofFIGURE 6.

Like elements are designated by like characters throughout thespecification and drawings. With specific reference now to the drawings,and in the first instance to FIGURE 1, the numeral 20 designates acylindrical sleeve-like support for the pump elements of the presentinvention. The sleeve 20 is adapted to be received within a housingindicated by the dash lines at 21. The opening or cavity in the housingwhich receives the sleeve 20 may be closed by a suitable cover 22. Adrive shaft 23 is adapted to be coupled to the pump elements carried bythe sleeve 20. The drive shaft 23, for example, may include a reducedend portion 24 which is received within a short ring or sleeve 25 in aslip fitting relation. Ring 25 is fixed to and fitted over a pressureplate assembly consisting of first and second plates 26 and 27. Itshould be understood that the plates 26 and 27 may be formed as oneintegral member although it is convenient to form the plates separatelyfrom metal stampings and then position them together as illustrated inthe drawings. The outer plate 26 may have a smaller diameter than plate27 so that the connecting sleeve 25 is received over plate 26 and inabutting relation to plate 27. An adapting ring 28 is received over thering or sleeve 25 and fills the space between the reduced portion of theshaft and the sleeve 20. The adapting ring 28 is fixed to the sleeve 20.It should be understood that the adapting ring 28 may be of varyingthicknesses in order to accommodate varying diameters of drive shafts.

The pumping elements of the pump include an outer ring gear 30 which isfixed to the pressure plates as by means of a coupling pin 31. Thepressure plates are in turn fixed to the drive shaft by means of a pin32 which is carried by the pressure plates and which is received withina bore 33 in the reduced end of the drive shaft. It should be noted thatthe bore 33 is longer than the pin 32 so that the pin 32 is slidablyreceived in the .bore 33. An inner gear 34 has lobes which areengageable with inwardly facing lobes on the outer ring gear. The innergear is supported for rotation on an idler shaft 35. Idler shaft 35 hasits axis offset from the axis of the drive shaft and the axis of theouter ring gear and is supported by a port plate 36. Port plate 36 aswell as the outer rin gear 30 are rotatably supported by the sleeve 20.A stationary port plate 37 is press fitted within the sleeve 20 and ispositioned adjacent to the side of the port plate remote from the outergear. One or more pins 38 are fixed to the plate 37 and are receivedwithin elongated bores 39 in the cover 22 so that the pins 38 areslidable with respect to the cover 22 in a direction parallel to theaxis of the pump While at the same time holding the plate 37 and sleeve20 against rotation. It should be understood that suitable cap screws orthe like are utilized to fix the cover 22 to the housing and theseelements are not shown because they are more or less conventional inapparatus of this general class.

The fixed port plate 37 hasan arcuate recess 40 formed therein and thisrecess extends for an arc of approximately This provides an inlet recessin the fixed plate 37.

The port plate 36 carries a stop pin 41 which is received within thisrecess and may rotate with the port plate 36 to and from the extremepositions illustrated in FIGURES 3 and 4. The fixed plate 37 also has acentral passage 42 formed in the face thereof which faces the port plateso that this passage may communicate through the hollow portion of theidler shaft 35, through apertures 43 in the pressure plates, and thencewith an outlet 44 formed through the drive shaft. Outlet 44 may lead toany suitable point of use (as for lubricating the bearings for shaft23).

The port plate has a pair of generally arcuate passages 45 and 47 formedtherethrough and on radii generally equal to the radii used to form thepassage 40 and generally equal to the outer portion of the enlargedpassage 42 in the fixed plate 37. These arcuate passages 45 and 47 inthe port plate are adapted to selectively overlap the passage 40 or thepassage 42 in the fixed plate 37 as is illustrated in FIGURES 3 and 4.FIGURES 3 and 4 illustrate different operative positions of the portplate to insure unidirectional flow from the passage 40 and to one orthe other of the arcuate passages 45 and 47 and to the outlet passage 42of the fixed plate.

An inlet passage 48 is formed in the cover 22 and may lead to a suitablesource of liquid to be pumped. This may be supplied through a conduitfitting which leads to housing 21 and to the inlet passage 48. Inletpassage 48 is adapted to communicate also with a relief valve passage 49which is formed centrally of the stationary port plate 37. This reliefpassage is normally closed by a spring biased valve 50. When pressurewithin the pump builds up beyond a predetermined desired maximum, thevalve 50 may yield against a spring 51 so as to allow return of fluid tothe inlet passage 48 from the outlet passage 42 of the fixed plate.

During operation of the pump, the drive shaft drives the pressure plates26 through the pin connection 32 and drives the outer ring gear throughthe pin connection 31. During rotation of the shaft and outer ring gearin one direction, as for example clockwise, in FIGURE 3, the frictionalengagement between the outer ring gear and port plate will insurerotation of the port plate to the position illustrated in FIGURE 3. Theclockwise frictional forces simply force the pin 41 of the port plate toa position of abutment with the end of the passage 40 in the fixed plate37. In this position, fluid flows from the inlet 48 through the fixedplate passage 40, then through the port plate passage 45 in overlappingrelation therewith and to the spaces between the lobes of the gears.Rotation of the gears impels the fluid around the axis of the pump to aposition circumferentially spaced from the port 45 and to the port 47where the pressure forces it through the port 47 and into the outletpassage 42 of the fixed plate. The pressure so developed results indirecting the fluid through the hollow idler shaft 35, then through theapertures 43 in the pressure plates and to the outlet 44.

If for some reason the drive shaft is rotated in the opposite directionas, for example, clockwise as illustrated in FIGURE 4, the frictionalforces on the port plate are then counterclockwise and cause rotation ofthe port plate to the position illustrated in FIGURE 4 where the stoppin 41 abuts against the other end wall of the passage 40 in the fixedplate. This shifts the connections of the ports in the fixed plate andthe port plate in that it brings the passage 47 into overlappingrelation with the passage 40 while the passage 45 is then in overlappingrelation to the passage 42. Thus, under either direction of rotation,the inlet passage 40 of the fixed plate is always in communication witha passage in the port plate leading to the lobes of the gears, while theoutlet passage 42 in the fixed plate is always in communication with apassage in the port plate on the pressure side of the lobes of thegears.

During the operating condition of the pump, the fluid pressure in theapertures 43 is directed against the end face of the drive shaft andthis causes the space between the end of the drive shaft and the plate26 to be filled with fluid under pressure. This forces the entire pumpcartridge comprised of the sleeve and all of the elements in the sleeveto the left in FIGURE 1 and tightly against the cover 22. This insuresthat the cartridge assembly is square to the face of the cover and helpsto properly maintain alignment between the pump cartridge axis and theaxis of the drive shaft. 1

When the pump is idle and no pressure condition is in the pump, thespring 51 may force the cartridge away from the cover and against theend of the pump shaft.

In FIGURES 6 and 7 a modified form of pump assembly is illustrated. Inthese figures, a pump cartridge is defined by a sleeve which rotatablysupports a port plate 61, outer gear 62, and pressure plate 63 forrotation therein. An inner gear 64 is journaled for rotation on a hollowshaft 65 which is fixed to and carried by the port plate 61.The'pressure plate may be defined by two separate plates as illustrated,or may be formed as a single element. The pressure plate 63 carries aprojecting sleeve 66 which is adapted to be snugly received over thereduced end portion 67 of the drive shaft 68. An adapting ring 69 isfixed to the sleeve 60 and fills the space between ring 66 and thesleeve. It should be understood that the adapting ring 69 may be made ofvarying sizes and ring 66 may have varying diameters depending upon thediameter of the end connecting portion of the shaft. A pin 70 is carriedby the outer gear 62 and projects through the pressure plate 63 and intoa bore 71 formed in the end of the drive shaft so as to connect thedrive shaft, pressure plates, and outer gear for rotation together as inthe case of the pump illustrated in FIGURES 1-5.

Sleeve 60 is adapted to be received within a pump cavity 72 formed insome housing member as at 21. The pump sleeve 60 is slidably received inthis cavity and relatively loose tolerances may be employed between thesleeve 60 and the wall defining the cavity.

In FIGURES 6 and 7 a cover 73 has a boss 74 which is slidably receivedwithin the end of sleeve 60 opposite to the drive shaft. The boss 74defines the port plate which is stationary. Cover 73 has an inlet 74awhich is adapted for selective communication with arcuately shaped andspaced passages 75 and 76 formed in the port plate 61 through an arcuaterecess 74b formed in the face of boss 74.

A passage 77 is formed through the side wall of the cover member andcommunicates with a passage 78 which is formed in the center of thecover member and which includes a portion 79 overlapping one or theother of the passages 75 and 76, as appears in FIGURE 7. A secondpassage 80 is formed through the side wall of the cover and is alignedwith passage 77. Passage 80 intersects passage 78. A spring biasedrelief valve 81 is seated in the passage 80 and bears against a valveseat 82 formed therein. The valve may be biased towards closed positionas illustrated by the spring 83. Spring 83 is held in position by plug84.

In FIGURES 6 and 7, the outlet from the pump may be formed through ashaft passage 85 whereby fluid under pressure developed by the gears 62and 64 passes from the space 79 through the hollow shaft 65 and throughthe pressure plate to the outlet passage 85. On the other hand, theoutlet 85 in the shaft may be eliminated and the passage 77 may then beused as a discharge passage. When using the outlet through the shaft,passage 77 is closed to the exterior as by means of a plug which isscrewthreaded into the threaded fitting 86 at the outer end of thispassage or a gauge may be fitted into fitting 86 to measure the pumppressure.

In either event, the pressure developed by the pump passes through theshaft 65 into the space between the end of the shaft and the pressureplate so as to bias the cartridge assembly towards the cover. Thisallows longer tolerances between the sleeve and the wall of the cavityin the housing as is the case with the pump of FIG- URES l-5.

The embodiment of FIGURES 6 and 7 may also be used without the use ofthe pressure within the pump to bias the pump elements towards the covermember while eliminating the advantage gained thereby. In this event,the boss of the cover member is press-fitted within the sleeve 60 orwelded thereto, in which case the pump cartridge as a whole is held inposition by the action of bolts or cap screws passed through bolt holes87 in the cover member.

In this event, the passage opening through the pressure plate 63 mayalso be closed.

In operation, the pump of FIGURES 6 and 7 operates in substantially thesame manner as the pump of FIG- URES 1-5. Rotation of the drive shaft inone direction as, for example, the counterclockwise direction as in FIG-URE 7, causes rotation of port plate 61 (through the frictional forcesdeveloped between the port plate 61 and the outer gear 62) to a positionwhere stop pin 88 abuts one end of the arcuate slot or passage 74b inthe cover member to thereby overlap the passage 75 with the passage 74awhile passage 76 is overlapped with passage 79. Upon rotation of thedrive shaft in the opposite direction, inlet port 74b is overlapped withthe arcuate port plate passage 76 which leads to the intergear spaceswhile passage 75 is connected to passage 79. Thus, one or the other ofthe ports 75 or 76 of the port plate is always in communication with theinlet port 74b while the other is in communication with the outletpassage 79 in the cover member. The arrangement of FIGURES 6 and 7 isalso such as to limit the amount of rotation of the port plate to on theorder of 90".

In both embodiments the thrust forces developed in the gears, which tendto act radially outwardly from the axis of the pump, are transmittedthrough the connecting ring 66 to the drive shaft. This minimizes theeffect of forces which might otherwise cause binding of the outer gearand port plate within the supporting sleeve. I

It may be noted that the travel of the stop pin for the port plate inboth forms of the invention covers an arc of approximately 90. This ismade possible by having the arcuate inlet passage in the stationary portmember relatively long as, for example, on the order of 90 asillustrated in both embodiments, while the outlet passage in thestationary port plate is also made sufficiently large to enable properselective connection to the passages in the rotatable port plate. Theactual travel of the stop pin may be minimized by placing the arcuatepassages relatively close to the central axis of the rotatable portplate, as illustrated in FIGURE 6. The enlargement of the passages inthe stationary port plate as well as the placement thereof inwardly ofthe outer marginal portions of the rotatable port plate and stationaryport plate enables this reduction of travel of the stop pin."Ihe amountof travel required of the stop pin may be further reduced by enlargingthe inlet passage in the stationary port plate to more than 90"; but inthis event the stop pin carried by the port plate must then fit within agroove in the stationary port plate which is separate from the inletpassage because, when the stop pin is positioned within the inletpassage of the stationary port plate, the amount of travel of the stoppin is determined by the arcuate length of the inlet passage. It ispreferred to have this amount of travel on the order of approximately 90as is illustrated in the drawings.

The reduction in travel of the stop pin reduces the inertia effects andshock forces when the port plate is shifted from that found in pumpsusing approximately 180 of travel.

Whereas I have shown and described an operative form of the invention,it should be understoodthat this showing and description thereof shouldbe taken in an illustrative or diagrammatic sense only. There aremodifications to the invention which will fall within the scope andspirit thereof and which will be apparent to those skilled in the art.The scope of the invention should be measured only by the scope of thehereinafter appended claims.

I claim:

1. A unidirectional flow cartridge assembled lobe gear pump including acylindrical supporting sleeve having pump elements including astationary port member, rotatable port plate, inner gear, and outer ringgear positioned therein, said stationary port member being fixed to saidsleeve, said rotatable port plate being positioned between saidstationary port plate and said outer ring gear, said rotatable portplate and said ring gear being supported for rotation by said sleeve,said rotatable port plate carrying a bearing for said inner gear, saidbearing being positioned eccentrically with respect to the axis of theouter gear, a pressure plate positioned within said sleeve and opposedto said outer ring gear, and means for fixing said outer ring gear andpressure plate together for unitary rotation thereof and for connectingsaid pressure plate to the end of a drive shaft, said stationary portplate and rotatable port plate having inlet and outlet passagescommunicating with the spaces between the lobes of the inner gear andouter gear and being shiftable to provide the same direction of flow offluid through an outlet of said pump irrespective of the direction ofrotation of the outer ring gear.

2. A unidirectional flow cartridge assembled lobe gear pump including asupporting sleeve having pump elements including a stationary portmember, rotatable port plate, inner gear, and outer ring gear positionedwithin said sleeve, said rotatable port plate being positioned betweensaid said stationary port plate and said outer ring gear, said rotatableport plate carrying a bearing for said inner gear, said bearing beingpositioned eccentrically with respect to the axis of the outer gear, apressure plate assembly positioned within said sleeve and opposed tosaid outer ring gear, means for fixing said outer ring gear and pressureplate assembly together for unitary rotation thereof and for connectingsaid pressure plate assembly to the end of a drive shaft, saidstationary port plate and rotatable port plate having inlet and outletpassages communicating with the spaces between the lobes of the innergear and outer gear and being shiftable to provide the same direction offlow of fluid through an outlet of said pump irrespective of thedirection of rotation of the outer ring gear, a shaft-adapting ringcarried within said sleeve and on the side of said pressure plateopposite to the outer ring gear, said shaft-adapting ring being adaptedto fit over the end of a drive shaft and being fixed to said pressureplate, and supporting means for said sleeve, said supporting meansallowing a limited amount of axial movement of said sleeve and pumpelements assembled therein relative thereto and relative to said driveshaft.

3. A unidirectional flow cartridge assembled lobe gear pump including anouter sleeve and pump elements including a stationary port member,rotatable port plate, inner gear, and outer ring gear within saidsleeve, said stationary port member being fixed to said sleeve, saidrotatable port plate being positioned between said stationary port plateand said outer ring gear, said rotatable port plate carrying a bearingfor said inner gear, said bearing being positioned eccentrically withrespect to the axis of the outer gear, a pressure plate assemblypositioned within said sleeve and opposed to said outer ring gear, andmeans for fixing said outer ring gear and pressure plate assemblytogether for unitary rotation thereof and for connecting said pressureplate assembly to the end of a drive shaft, said stationary port plateand rotatable port plate having inlet and outlet passages communicatingwith the spaces between the lobes of the inner gear and outer gear, saidrotatable port plate being rotatable within said sleeve to provide thesame direction of flow of fluid through an outlet of said pumpirrespective of the direction of rotation of the outer ring gear, ahousing surrounding said sleeve and the end of said stationary portplate, and means aligning said sleeve and stationary port plate withinsaid housing and preventing relative rotation thereof while allowingaxial movement of said sleeve and pump elements relative to saidhousing.

4. The structure of claim 3 wherein said last named means includes pinscarried by said stationary port plate and received within bores in aportion of the housing opposed thereto.

5. The structure of claim 3 wherein said pump has an outlet passagecommunicating through the pressure plate and against the end of a driveshaft opposed thereto and fixed to the pressure plate to thereby createpressure between the end of the drive shaft and pressure plate and forcesaid assembled pump elements away from said drive shaft for a limitedextent.

6. The structure of claim 5 wherein the means for connecting saidpressure plate and outer ring gear to said drive shaft includes a pincarried by said pressure plate and received within a bore in the end ofsaid drive shaft while allowing relative axial movement between thedrive shaft and sleeve and elements therein.

7. The structure of claim 6 characterized by and including ashaft-connecting ring carried by said pressure plate and received overthe end of said drive shaft, said ring being positioned between theshaft and said sleeve.

8. A unidirectional flow gear pump assembly including a housing having apump cavity therein with a cover at an end of the cavity, a pumpingelement supporting sleeve within said cavity in confronting relation tosaid cover, said sleeve having gear means rotatably supported thereinfor pumping fluid during rotation of said gear means and porting meanstherein for delivering fluid from an inlet in the housing to an outlettherefrom irrespective of the direction of rotation of said gear means,a drive shaft for said gear means for rotating said gear means, meansconnecting the shaft and gear means for rotation together while allowinglimited axial relative movement between said shaft and said gear meansto thereby allow definition of a space at the end of said shaft, meansestablishing communication between said outlet and said space, and meansholding said sleeve against rotation relative to said cover and housingwhile allowing axial movement of said sleeve relative to said cover andhousing, whereby pressure in said space forces said sleeve into squarerelation with said cover.

9. The structure of claim 8 wherein said shaft has an outlet passageformed therein and in communication with said space.

10. The structure of claim 8 wherein an outlet passage is formed in saidcover and in communication with the outlet side of said porting meansirrespective of the direction of rotation of said gears.

11. The structure of claim 8 wherein said cover includes a bossprojecting within said sleeve.

12. A unidirectional flow cartridge assembled lobe gear pump including asupport and a stationary port member, rotatable port plate, inner gear,and outer ring gear positioned with said support, said rotatable portplate being positioned between said stationary port plate and said outerring gear, said rotatable port plate carrying a bearing for said innergear, said bearing being positioned eccentrically with respect to theaxis of the outer gear, means for connecting said outer ring gear to theend of a drive shaft, said stationary port plate and rotatable portplate having inlet and outlet passages in selective communication withone another and communicating with the spaces between the lobes of theinner gear and outer gear, said rotatable port plate being shiftable toprovide the same direction of flow through an outlet of said pumpirrespective of the direction of rotation of the outer ring gear, saidpassages being formed inwardly of the outer marginal portions of thestationary port plate and the rotatable port plate, means limiting therotation of said rotatable port plate to substantially less than 180,said passages having arcuate lengths such as to provide saidcommunication.

13. The structure of claim 12 wherein said stationary port plate has aninlet passage therein alignable selectively with a pair of spacedpassages in said rotatable port plate, said rotatable port plate havinga stop pin projecting within said inlet passage, said inlet passagebeing formed as an are on the order of there-by to limit the travel ofthe stop pin and rotatable port plate to on the order of approximately90.

14. The structure of claim 12 wherein said stationary port plate has aninlet passage therein formed as an elongated arcuate passage, saidrotatable port plate and stationary port plate having stop pin andelongated groove means receiving said stop pin for limiting rotation ofsaid rotatable port plate, the arcuate length of said groove means beingsuch as to limit travel of the rotatable port plate to on the order ofapproximately 90, the length of said inlet passage being such as toselectively connect with one of a pair of passages in said rotatableport plate when said rotatable port plate is rotated to one of itsextreme positions.

References Cited UNITED STATES PATENTS 2,380,783 7/ 1945 Painter.3,165,066 1/1965 Phelps et al. 3,208,392 9/ 1965 Garrison et al.3,272,128 9/ 1966 Brundage. 3,303,784 2/1967 Neubauer.

WILLIAM L. FREEH, Primary Examiner W. J. GOODLIN, Assistant Examiner US.Cl. X.R. 103-117

